This invention provides compounds, compositions and methods for the recovery of hydrocarbon fluids from a subterranean reservoir. More particularly, this invention concerns water-soluble branched polyhydroxyetheramines that modify the permeability of subterranean formations and increase the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.
The production of large amounts of water from oil and gas wells constitutes one of the major expenses in the overall recovery of hydrocarbons from a subterranean formation. Many producing oil wells produce a gross effluent having greater than 80% by volume water. Therefore, most of the pumping energy is expended by lifting water from the well. Then the production effluent must be subjected to expensive separation procedures in order to recover water-free hydrocarbons. The water constitutes a troublesome and an expensive disposal problem.
Therefore, it is highly desirable to decrease the amount of water produced from oil and gas wells. Another beneficial effect of decreasing the amount of produced water is realized by decreasing the flow of water in the well bore at a given pumping rate thereby lowering the liquid level over the pump in the well bore, thereby reducing the back pressure in the formation and improving pumping efficiency and net daily oil production.
We have discovered a family of novel branched polyhydroxyetheramine polymers that effectively reduce the amount of water recovered from subterranean, hydrocarbon-bearing formations, thereby increasing the production rate of hydrocarbons from the formation. The polymers of this invention are particularly effective at decreasing the water permeability with little effect on the oil permeability. Ester comb polymers decrease the water permeability but also significantly reduce the oil permeability. The polymers of this invention are also particularly effective for use in gas and oil wells that operate at temperatures higher than about 200xc2x0 F. where polymers such as polyacrylamide (PAM), hydrolyzed polyacrylamide (HPAM) and ester-containing polymers are less effective due to hydrolysis of the ester or amide-functionality.
Accordingly, in its principal aspect, this invention is directed to a water-soluble branched polyhydroxyetheramine, wherein the branched polyhydroxyetheramine is prepared by reacting an amine having two reactive hydrogen atoms with a diepoxide to form a polyhydroxyetheramine and then reacting the polyhydroxyetheramine with an N-alkylating agent.
xe2x80x9cAcylxe2x80x9d means a group of formula Rxe2x80x2C(O)xe2x80x94where Rxe2x80x2 is C1-C8 alkyl. C1-C2 alkyl groups are preferred. Representative acyl groups include acetyl, propionyl, butyryl, and the like.
xe2x80x9cAlkoxyxe2x80x9d means a C1-C8 alkyl group attached to the parent molecular moiety through an oxygen atom. Representative alkoxy groups include methoxy, ethoxy, propoxy, butoxy, and the like. Methoxy and ethoxy are preferred.
xe2x80x9cAlkylxe2x80x9d means a monovalent group derived from a straight or branched chain saturated hydrocarbon by the removal of a single hydrogen atom. Representative alkyl groups include methyl, ethyl, n- and iso-propyl, n-, sec-, iso- and tert-butyl, and the like.
xe2x80x9cAlkylamidoxe2x80x9d means a group of formula Rxe2x80x2NHC(O)xe2x80x94where Rxe2x80x2 is C1-C8 alkyl. C1-C2 alkyl groups are preferred.
xe2x80x9cAlkylcarbonylxe2x80x9d means a C2-C8 alkyl group where the alkyl chain is interrupted with a carbonyl ( greater than Cxe2x95x90O) group (i.e. an alkyl-C(O)-alkylene-group). Representative alkylcarbonyl groups include methylcarbonymethyl, ethylcarbonylmethyl, methylcarbonylethyl, (2-methylpropyl)carbonylmethyl, and the like.
xe2x80x9cAlkylenexe2x80x9d means a divalent group derived from a straight or branched chain saturated hydrocarbon by the removal of two hydrogen atoms, for example methylene, 1,2-ethylene, 1,1-ethylene, 1,3-propylene, 2,2-dimethylpropylene, and the like.
xe2x80x9cAmine having two reactive hydrogen atomsxe2x80x9d means an amine having two Nxe2x80x94H groups, where the Nxe2x80x94H groups are sufficiently reactive to react with the epoxide groups of a diepoxide as defined herein to form a polyhydroxyetheramine. The amine having two reactive hydrogen atoms may be a primary amine, or a compound containing two secondary amino groups, where the compound containing two secondary amino groups may be cyclic or acyclic. The amine having two reactive hydrogen atoms is optionally substituted with one or more with alkylamido, dialkylamino, hydroxy, hydroxyalkyl, alkoxy, halo, cyano, aryloxy, alkylcarbonyl or arylcarbonyl groups.
xe2x80x9cArylxe2x80x9d means substituted and unsubstituted aromatic carbocyclic radicals and substituted and unsubstituted heterocyclic having from 5 to about 14 ring atoms. Representative aryl include phenyl naphthyl, phenanthryl, anthracyl, pyridyl, furyl, pyrrolyl, quinolyl, thienyl, thiazolyl, pyrimidyl, indolyl, and the like. The aryl is optionally substituted with one or more alkylamido, hydroxy, alkoxy, halo, cyano, aryloxy, alkylcarbonyl or arylcarbonyl groups.
xe2x80x9cArylalkylxe2x80x9d means means an aryl group attached to the parent molecular moiety through a C1-C8 alkylene group. C1-C2 alkylene groups are preferred. Representative arylalkyl groups include phenylmethyl, phenylethyl, phenylpropyl, 1-naphthylmethyl, and the like.
xe2x80x9cArylcarbonylxe2x80x9d means an aryl group attached to the parent molecular moiety through a carbonyl group. Representative arylcarbonyl include benzoyl and substituted benzoyl.
xe2x80x9cAryloxyxe2x80x9d means an aryl group attached to the parent molecular moiety through an oxygen atom. Representative aryloxy groups include phenoxy, pyridyloxy, and the like.
xe2x80x9cCycloalkylenexe2x80x9d means a divalent group derived from a saturated carbocyclic hydrocarbon by the removal of two hydrogen atoms, for example cyclopentylene, cyclohexylene, and the like.
xe2x80x9cDialkylaminoxe2x80x9d means a group having the structure xe2x80x94NRxe2x80x2Rxe2x80x3 wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from C1-C8 alkyl. C1-C2 alkyl are preferred. Additionally, Rxe2x80x2 and Rxe2x80x3 taken together may optionally be xe2x80x94(CH2)kxe2x80x94 where k is an integer of from 2 to 6. Examples of dialkylamino include, dimethylamino, diethylaminocarbonyl, methylethylamino, piperidino, and the like.
xe2x80x9cHaloxe2x80x9d and xe2x80x9chalogenxe2x80x9d mean chlorine, fluorine, bromine and iodine.
xe2x80x9cDiepoxidexe2x80x9d means a cyclic or acyclic compound containing two epoxide groups. Representative diepoxides include diglycidyl esters of diacids, diglycidyl ethers of diols, epoxidized olefins, and the like.
xe2x80x9cDiglycidyl ester of a diacidxe2x80x9d means a diepoxide of formula 
where R6 is C2-C36 alkylene or C5-C8 cycloalkylene, where the alkylene is optionally interrupted with a cylcloalkylene group, and where the alkylene or cycloalkylene is optionally substituted with one or more alkylamido, hydroxy, alkoxy, halo, cyano, aryloxy, alkylcarbonyl or arylcarbonyl groups. A preferred diglycidyl ester of a diacid is diglycidyl ether of dimer acid.
xe2x80x9cDiglycidyl ether of a diolxe2x80x9d means a compound of formula 
where R7 is C2-C20 alkylene or C2-C40 alkoxy, where the alkylene is optionally interrupted with a cycloalkylene group and the alkylene or alkoxy is optionally substituted with one or more alkylamido, hydroxy, alkoxy, halo, cyano, aryloxy, alkylcarbonyl or arylcarbonyl groups. Preferred diglycidyl ethers of a diol include bis(2,3-epoxypropyl)ether, diglycidyl ether of 1,4-butanediol, diglycidyl ether of neopentyl glycol, diglycidyl ether of ethylene glycol, glycerol diglycidyl ether, diglycidyl ether of polyethyleneglycols, diglycidyl ether of polypropylene glycols, diglycidyl ether of glycols from the reaction of ethylene oxide with propylene oxide, diglycidyl ether of cyclohexane dimethanol, and the like.
xe2x80x9cEpoxidized olefinxe2x80x9d means a compound of formula 
where R9 is C2-C20 alkylene, where the alkylene is optionally interrupted with a cylcloalkylene group and optionally substituted with one or more alkylamido, hydroxy, alkoxy, halo, cyano, aryloxy, alkylcarbonyl or arylcarbonyl groups and R8 and R10 are H or R8 and R10 are connected through a valence bond to form a C6-C20 cycloalkyl. Representative epoxidized olefins include 1,2,3,4-diepoxybutane; 1,2,7,8-diepoxyoctane, 1,2,9,10-diepoxydecane, 1,2,5,6-diepoxycyclooctane, and the like.
xe2x80x9cHydroxyalkylxe2x80x9d means a C1-C8 alkyl substituted by one to three hydroxyl groups with the proviso that no more than one hydroxy group may be attached to a single carbon atom of the alkyl group. Representative hydroxyalkyl include hydroxyethyl, 2-hydroxypropyl, and the like.
xe2x80x9cTriepoxidexe2x80x9d means an acyclic compound containing three epoxide groups. Representative triepoxides include trimethyol propane triglycidyl ether, polyglycidyl ether of castor oil, polyglycidyl ether of an aliphatic polyol, and the like.
xe2x80x9cN-Alkylating agentxe2x80x9d means a compound of formula R11X where X is halogen, sulfate or sulfonyl and R11 is C5-C24 alkyl or alkenyl. The alkyl or alkenyl group is optionally interrupted with one or more oxygen atoms, provided that no two oxygen atoms are bonded directly to one another, optionally substituted with one or more hydroxy or aryl groups. Representative N-alkylating agents include halogen-containing polyalkoxides as defined herein; alkyl halides including 1-bromooctane, 1-chlorooctane, 1-chlorohexadecane, 1-chlorooctadecane, 1-bromooctadecane, 1-bromohexadecane, and the like; alcohol sulfonates including sodium lauryl sulfonate, sodium laureth sulfate, sodium octyl sulfate, and the like; and alpha olefin sulfonates including C16-C18 olefin sulfonate, C14-C16 olefin sulfonate, C12-C14 olefin sulfonate, and the like.
xe2x80x9cHalogen containing polyalkoxidexe2x80x9d means a compound of formula 
where Y is halogen; R12 is H, C1-C6 alkyl, aryl, hydroxyalkyl, or 2,3-epoxypropyl; R14 is straight-chain C2-C24 alkyl, optionally substituted with one or more hydroxy or C1-C6 alkyl groups. Representative polyalkoxides include polyethylene oxide, polypropylene oxide, polybutylene oxide, polyethylenepropylene oxides and mixtures thereof, and the like.
Preferred Embodiments
The branched polyhydroxyetheramines of this invention are prepared by reacting an amine having two reactive hydrogen atoms with a diepoxide to form a polyhydroxyetheramine and then reacting the polyhydroxyetheramine with an N-alkylating agent.
In preparing the polyhydroxyetheramine, the reactants are generally employed in a mole ratio of amine having two reactive amino hydrogens to diepoxide of about 0.5:1 to about 1.4:1, preferably about 0.8:1 to about 1.1:1 and more preferably 0.9:1 to about 1.05:1.
The reaction of the amine and the diepoxide is very exothermic and typically requires a solvent and cooling to control the exothermic nature when prepared in a batch reactor. Suitable solvents include water, ether and alcohols such as di(propylene glycol) methyl ether, 2-methoxyethyl ether and the like. Preferably, the initial reaction is conducted under a blanket of nitrogen or another inert gas, preferably at a temperature of about 25xc2x0 C. to about 240xc2x0 C., more preferably at a temperature of about 25xc2x0 C. to about 150xc2x0 C. and still more preferably at a temperature of about 25xc2x0 to about 100xc2x0 C. After the exotherm, subsequent reaction is carried out between 140xc2x0 C. and 200xc2x0 C., preferably between 140xc2x0 C. and 180 xc2x0 C. and more preferably between 140xc2x0 C. and 160xc2x0 C. for about 10 minutes to about 100 hours depending on the viscosity desired for the final product. The reaction can be conducted neat in a batch reactor or in an extruder.
In a preferred aspect of this invention, the amine having two reactive hydrogen atoms is selected from the group consisting of amines of formula (a)-(g) 
Wherein R is C2-C10 alkylene, optionally substituted with one or more hydroxy or hydroxyalkyl groups; R1 is independently selected at each occurrence from a group of formula (xe2x80x94CH2xe2x80x94CH2xe2x80x94Oxe2x80x94)p and a group of formula 
R2 is C2-C10 alkylene, optionally substituted with alkylamido, hydroxy, alkoxy, halo, cyano, dialkylamine, aryloxy, alkylcarbonyl or arylcarbonyl; R3 is C2-C20 alkylene optionally substituted with alkylamido, hydroxy, alkoxy, halo, cyano, aryloxy, alkylcarbonyl or arylcarbonyl; R4 is alkoxy; R5 is H or xe2x80x94CH3; Z is hydrogen, alkylamido, hydroxy, dialkylamine, alkoxy, halo, aryoxy, cyano, alkylcarbonyl, or arylcarbonyl; Z1 is hydrogen, C1-C7 alkyl or acyl; and n, p, q and r are independently integers of 1 to about 45.
Amines of formula (a)-(g) are commercially available from a variety of sources including Aldrich Chemicals, Milwaukee, Wis.; Angus Chemical Company, Buffalo Grove, Ill.; Air Products and Chemicals, Inc., Allentown, Pa.; Ashland Distribution Company, Columbus, Ohio; Dow Chemical Company, Midland, Mich.; Fleming Labs, Inc, Charlotte, N.C.; Huntsman Corporation, Houston, Tex.; Union Carbide Corporation, Danbury, Conn.; and others.
In another preferred aspect, R is methylene or ethylene; R2 is ethylene; R3 is C2-C20 alkylene optionally substituted with alkylamido, dialkylamino, hydroxy or alkoxy; and Z is alkylamido, dialkylamino, hydroxy or alkoxy.
In another preferred aspect, the amine is selected from the group consisting of methylamine; ethylamine; propylamine; butylamine; sec-butylamine; isobutylamine; 3,3-dimethylbutylamine; hexylamine; benzylamine; 2-amino-1-butanol; 4-amino-1-butanol; 2-amino-2-methyl-1-propanol; 6-amino-1-hexanol; ethanolamine; propanolamine; tris(hydroxymethyl)aminomethane; 1-amino-1-deoxy-D-sorbitol; 3-amino-1,2-propanediol; 2-amino-2-methyl-1,3-propanediol; 2-amino-2-ethyl-1,3-propanediol; 3-(dimethylamino)propylamine; N,N-dimethylethylenediamine; N,N-diethylethylenediamine; 1-(2-aminoethyl)piperidine; 4-(2-aminoethyl)morpholine; 2-(2-aminoethyl)-1-methylpyrrolidine; 1-(2- aminoethyl)pyrrolidine; 2-(2-aminoethyl)pyridine; 2-(2-aminoethoxy)ethanol; 2-(2-aminoethylamino)ethanol; piperazine, 2-methyl piperazine, 2,6-dimethylpiperazine; 2-(methylamido)piperazine; N,Nxe2x80x2-bis(2-hydroxyethyl)ethylenediamine, N,Nxe2x80x2-dimethylethylenediamine, N,Nxe2x80x2-dimethyl-1,4-phenylenediamine and N,Nxe2x80x2-dimethyl-1,6-hexanediamine.
In another preferred aspect, the diepoxide is selected from the group consisting of diglycidyl esters of diacids, diglycidyl ethers of diols and epoxidized olefins.
In another preferred aspect, the diepoxide is selected from the group consisting of diglycidyl ether of dimer acid, bis(2,3-epoxypropyl)ether, diglycidyl ether of 1,4-butanediol, diglycidyl ether of neopentyl glycol, diglycidyl ether of ethylene glycol, glycerol diglycidyl ether, diglycidyl ether of polyethyleneglycols, diglycidyl ether of polypropylene glycols, diglycidyl ether of glycols from the reaction of ethylene oxide with propylene oxide, diglycidyl ether of cyclohexane dimethanol, 1,2,3,4-diepoxybutane; 1,2,7,8-diepoxyoctane, 1,2,9,10-diepoxydecane and 1,2,5,6-diepoxycyclooctane.
In another preferred aspect of this invention, aliphatic triepoxides can be mixed with the diepoxides to provide crosslinking. Suitable aliphatic triepoxides are trimethyol propane triglycidyl ether, polyglycidyl ether of castor oil and polyglycidyl ether of an aliphatic polyol.
We have discovered that the presence of mine, tertiary amine or ditertiary amine end groups in the polyhydroxyetheramine is preferred as opposed to an epoxide end group in order to improve solubility in water and alcohol solvents and prevent continuing reaction.
Secondary amine end groups are obtained from the reaction of the remaining unreacted epoxide groups with the above amines having two available amino hydrogens at a concentration of 2 to 5 mole % excess amine.
Tertiary amine end groups are obtained by reacting the unreacted epoxide groups with amines having one available amino hydrogen such as diethanolamine, diisopropanolamine, N-methyl-D-glucamine, N-methylpropylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine and the like.
Ditertiary amine end groups are obtained by reacting the unreacted epoxide groups with amines having one available amino hydrogen substituted with a tertiary amine group such as N,N,Nxe2x80x2-trimethyl-1,3-propanediamine, N,N,Nxe2x80x2- trimethylethylenediamine, N,N-dimethyl-Nxe2x80x2-ethylethylenediamine, N,N,Nxe2x80x2-triethylethylenediamine and the like. Ditertiary amine end groups also provide extended tertiary amine groups for grafting N-alkylating agents onto the polyhydroxyetheramine backbone.
The backbone polyhydroxyetheramine formed by reaction of the amine with two reactive amino hydrogens and the diepoxide varies in percent solids from about 20 to 100, preferably from about 50 to about 80 and more preferably from about 60 to about 70 weight percent in a suitable solvent such as an alcohol or ether.
Side chains or branches are attached to the polyhydroxyetheramine backbone by reaction with one or more N-alkylating agents.
In a preferred aspect of this invention, the N-alkylating agent is selected from the group consisting of halogen-containing polyalkoxides, alkyl halides, alcohol sulfonates and alpha olefin sulfonates.
In another preferred aspect, the N-alkylating agent is a halogen containing polyalkoxide.
We have discovered that a low percentage of the tertiary amines in the polyhydroxyetheramine backbone polymer can be grafted with the N-alkylating agent. However, if the amine having two reactive amino groups used to prepare the polyhydroxyetheramine backbone polymer is substituted with a tertiary amine group to give an extended tertiary amine, a much higher percentage of the N-alkylating agent can be reacted. Examples of such amines having two reactive amino groups and substituted with a tertiary amine group are 3-(dimethylamino)propylamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, 1-(2-aminoethyl)piperidine, 4-(2-aminoethyl)morpholine, 2-(2-aminoethyl)-1-methylpyrrolidine, 1-(2-aminoethyl)pyrrolidine, and 2-(2-aminoethyl)pyridine. Extended tertiary amines for reaction with N-alkylating agent can also be provided by the previously mentioned ditertiary amine end groups.
The amount of the amine having two reactive amino hydrogen atoms and a tertiary amine group comprises 0 to about 50 mole percent of the total amines having two reactive amino hydrogen atoms reacted with the diepoxide, depending on which amine having two reactive amino hydrogen atoms and a tertiary amine group is reacted. For example, 3-(dimethylamino)propylamine comprises 0 to about 10, preferably 0 to about 6 and more preferably 0 to about 2 mole percent of the total amines having two reactive amino hydrogens because it contains some methylaminopropylamine which crosslinks.
The N-alkylating agents are grafted onto tertiary amine groups on the polyhydroxyetheramine backbone polymer at a temperature of about 40xc2x0 C. to about 100xc2x0 C., preferably about 60xc2x0 C. to about 95xc2x0 C. and more preferably between about 85xc2x0 C. and about 90xc2x0 C. The higher the grafting temperature, the faster the grafting rate.
The rate of the grafting reaction is also influenced by pH. The reaction is carried out at a pH of about 7.5 to about 12.0, preferably about 8.0 to about 9.0 and more preferably about 8.4 to about 8.8.
The polyhydroxyetheramine polymer can be directly reacted with the N-alkylating agent or the polyhydroxyetheramine can be reacted with an acid, such as hydrochloric acid or sulfuric acid and then reacted with the N-alkylating agent.
The resulting grafted polymer varies in percent solids from about 20 to about 60, preferably about 25 to about 50 and more preferably about 35 to about 50 weight percent in water, ether or alcohol solvent.
One method of following the rate of the grafting reaction is to monitor the viscosity. When the viscosity of the graft polymer reaches about 200 cps to about 6000 cps, preferably about 2000 cps to about 5000 cps and more preferably about 4000 cps to about 5000 cps, the grafting reaction is usually stopped by adding a mixture of acid and salt water to reach an acidic pH, preferably about pH 2.0 to about 6.0 and more preferably about 3.5 to about 5.0. Sulfuric acid or hydrochloric acid are the preferred acids.
Preferred water-soluble branched polyhydroxyetheramines according to this invention include, but are not limited to diethanolamine capped ethanolamine/diglycidyl ether of neopentyl glycol copolymer grafted with epichlorohydrin terminated polyethyleneglycol methyl ether; N,N,Nxe2x80x2-trimethyl-1,3-propanediamine capped ethanolamine/3-(dimethylamino)propylamine/diglycidyl ether of neopentyl glycol terpolymer grafted with epichlorohydrin terminated polyethyleneglycol methyl ether polymer; diethanolamine capped 3-(dimethylamino)propylamine/ethanolamine/poly(ethylene glycol) diglycidyl ether terpolmer grafted with epichlorohydrin terminated polyethyleneglycol methyl ether; and diethanolamine capped 3-(dimethylamino)propylamine/ethanolamine/ethylene glycol diglycidyl ether terpolymer grafted with epichlorohydrin terminated polyethyleneglycol methyl ether.
In another aspect, this invention is directed to a method of modifying the permeability to water of a subterranean formation comprising injecting into the subterranean formation an aqueous composition comprising from about 0.005 percent to about 2 percent, by volume, of a water-soluble branched polyhydroxyetheramine, wherein the branched polyhydroxyetheramine is prepared by reacting an amine having two reactive hydrogen atoms with a diepoxide to form a polyhydroxyetheramine and then reacting the polyhydroxyetheramine with an N-alkylating agent.
The aqueous composition comprising branched polyhydroxyetheramine polymers of this invention are applied to the formation by forcing, injecting or pumping composition directly into the formation to be treated so that the polymer contacts or treats the formation or the desired portion of the formation to alter the permeability of the formation as desired.
Particulate material (e.g. sand, silica flour and asbestos) can also be added to or suspended in the aqueous composition.
The treatment of a subterranean formation through an oil well can be accomplished using one or more liquid spacers, preflushes or afterflushes, such as a dilute salt solution and/or an aqueous alkali metal halide solution, into the formation to pretreat or clean the formation, then injecting the aqueous composition of this invention in an amount calculated to contact the desired portion of the formation with the branched polyhydroxyetheramine polymer.
In another aspect of this invention, the N-alkylating agent and the polyhydroxyetheramine backbone polymer can also be mixed and pumped as a preflush ahead of a fracture-stimulation treatment before these components can react. In-situ reaction of the individual components allows deeper penetration of high-permeability strata from which undesired water flow typically occurs. The water-thin viscosity of the N-alkylating agent and polyhydroxyetheramine backbone polymer allows lower placement pressures.
In a preferred aspect, the polyhydroxyetheramine backbone polymer is prepared by the reaction of an amine with two reactive hydrogen with a diepoxide as defined herein.
After the polymer preflush is injected and the fracturing treatment placed, the well is shut in for about 10 to 18 hours, allowing the N-alkylating agent and polyhydroxyetheramine polymer to react. In some cases this polymer preflush can be preceded by a solvent preflush that removes asphaltene and paraffin deposits in the formation.
The foregoing may be better understood by reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of this invention.